1. Technical Field
The present invention is directed to supplemental data generation for complementing adjacent lines of real data, wherein the adjacent lines of data would otherwise be printed in a noncontiguous manner; that is, the adjacent lines of data would otherwise be printed with a gap therebetween.
The present invention is embodied in a facsimile recording device wherein data is printed on a line-by-line basis using a printing head such as a thermal or electrostatic printing head. The present invention generates supplemental data to be inserted in the gap between the adjacent lines of facsimile data in order to improve the visual quality of the facsimile print-out.
2. Background Information
The transmission and reception of data between facsimile devices is well know to those skilled in the art, the standard of transmission having been set world-wide by the International Telegraph and Telephone Consultative Committee (CCITT). The vertical resolution standard set by the CCITT is 3.85 lines per millimeter for standard resolution, and 7.7 lines per millimeter for optional resolution.
Typically, facsimile devices print facsimile data on a line-by-line basis using a thermal printing head whose width is at least as wide as the line to be printed. Employing the above resolution standards, adjacent lines of facsimile data are noncontiguous; that is, there is a gap which lies between the adjacent lines. Because of this, the printed quality is visually poor.
In order to compensate, the prior art has developed supplemental data generation techniques for printing supplemental data lines of data between the adjacent lines of facsimile data in order to visually improve the quality of the facsimile printout. For example, with reference to FIG. 1, a plurality of supplemental data lines are inserted between adjacent lines of real data in order to mask the gap between adjacent lines. In the most common technique, as shown in FIG. 1(a) and described in Japanese Laid Open Application No. 49-52514 assigned to the NEC Corporation, herein incorporated by reference, a first line of facsimile data is repeatedly printed until the receipt of a second line of facsimile data, at which point the second line is repeatedly printed until the reception of a third line. This process continues until all real lines of facsimile data have been printed.
Other techniques have also been employed by the prior art to mask the gap between adjacent lines of facsimile data. For example, the "sum" technique, shown in FIG. 1(b) and described in Japanese Laid Open Application No. 51-35215 and assigned to the same assignee as the present invention, herein incorporated by reference, prints supplemental lines comprising the summation of the adjacent lines of facsimile data. The "difference" technique, shown in FIG. 1(c) and described in the 51-35215 Application, prints supplemental lines comprising the difference between the adjacent lines of facsimile data.
The prior art techniques for generating supplemental data are adequate in situations where the adjacent lines are substantially linear in the vertical direction. However, the prior art produces poor results when the transmission to be printed contains substantial amounts of curvilinear data, as typically found in pictorial drawings and the character set of most alphabets, especially Arabic, Chinese and Japanese.